between the tympanic membrane and the promontory/round win- dow. The introduction of such a compressible pocket would restore hearing by allowing sound-induced motion of the tympanic mem- brane, ossicles and round window. The implant would be indicated in patients with chronic otitis media and a conductive hearing loss due to non-aeration of the middle ear. Background: Previous studies have shown that a small amount of air can facilitate middle-ear function in human temporal bones and hearing in patients with fluid-filled middle ears. A successful middle ear balloon implant must possess the following requisite characteristics: (1) Barrier properties: impermeable to air and body fluids, thereby allowing it to remain inflated for long time periods. (2) Acoustic properties: compressible by sound vibrations. (3) Biocompatibility: non-toxic and not biodegradable by the host response of the middle ear. Mate- rial and methods: Prototype implants (5 Â 3 Â 2 mm) comprising a thin biocompatible polymeric wall enclosing an air volume of 20 microliters were fabricated. Results: (1) Bench testing showed stable barrier properties under continuous immersion in saline for over 30 months. (2) Acoustic admittance measurements demonstrated that the balloons had equivalent air volumes between 50% and 90% of their physical volumes. In cadaveric temporal bones, in which filling the middle ear with saline produced a 30–35 dB decrease in umbo velocity, introducing balloon implants restored umbo velocity. The improvement in umbo velocity was roughly proportional to the total equivalent volume of the implants. (3) Implantation of balloons in chinchilla middle ears has shown no evidence of a host response or toxicity after six months. Conclusion: The middle-ear balloon im- plant may be a viable treatment for conductive hearing loss due to non-aeration of the middle ear. Funding: Work supported by NIDCD, Boston Medical Products, and donations to the MEEI. doi:10.1016/j.heares.2010.03.018 Extracellular bone matrix components on titanium prostheses induce osseointegration on the stapes footplate Marcus Neudert 1 , Thomas Beleites 1 , Anne Kluge 1 , Nikoloz Lasurashvili 1 , Dieter Scharnweber 2 , Thomas Zahnert 1 1 Clinic of Otorhinolaryngology, Department of Medicine, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; 2 Max-Bergmann-Center of Biomaterials, Technische Universität Dresden, Budapester Str. 27, 01062 Dresden, Germany Background: Save and stable coupling between prostheses and the ossicular remnants is crucial for good postoperative hearing results after ossiculoplasty. To establish a stable fixed-point on the stapes footplate for subsequent prosthesis reconstruction, a titanium foot- plate anchor was coated with components of the extracellular bone matrix to induce a controlled osseointegration on the footplate. Materials and methods: Specially designed titanium footplate anchors were implanted on the stapes footplate of one-year-old Merino sheep. The implants’ surfaces were modified by applying a collage- nous matrix with bone morphogenic protein (BMP-4) and trans- forming growth factor-b (TGF-b) to stimulate osteoblastic differentiation and activation on the stapes footplate with subse- quent osseointegration. Brainstem evoked response audiometry was used to observe hearing and polychrome labeling was used to assess new bone formation and remodeling during the study. After study termination on day 84 synchrotron radiation based computed microtomography and histomorphometry were used to identify bone implant contact. Results: During the study bone conduction thresholds remained stable in all groups. Histologically, an osseoin- tegration of the implanted prostheses was observed in two surface coated specimens. There was radiographical evidence for another eight implants to be integrated into newly formed bone. A footplate fixation in the oval niche by an excessive bone formation was never observed. Conclusions: These results prove the general ability to induce a controlled osseointegration of titanium implants on the sta- pes footplate in a mammalian organism. Once a bone fixed anchor is established on the footplate further individual prosthetic assemblies could improve middle ear reconstruction. doi:10.1016/j.heares.2010.03.019 Microstructuring and bioactive nanolayer coating of titanium surfaces for middle ear ossicular replacement prosthesis Justus Ilgner 1 , Slavomir Biedron 1 , Elena Fadeeva 2 , Doris Klee 1 , Martin Westhofen 1 1 University of Aachen RWTH, Aachen, Germany; 2 Laser Zentrum Hannover e.V., Hannover, Germany Introduction: While a variety of materials have been evaluated for replacement of human middle ear ossicles following inflamma- tion, titanium and its alloys have shown excellent sound transmis- sion properties and biocompatibility. However, cartilage thickness at the tympanic membrane interface deteriorates over time, while fibrous tissue formation may dislodge the titanium prosthesis. This study was performed to evaluate the effect of microstructures and bioactive nanolayer coating on titanium surfaces in contact with adjacent biological tissue. Materials and methods: Titanium samples of 5 mm diameter and 0.25 mm thickness were structured by means of a Ti:Sapphire femtosecond laser operating at 970 nm. The structures applied were lines of parabolic shape (cross-sec- tional) of 5 lm (parallel), 5 lm (cross-hatch) and 10 lm width (parallel). The inter-groove distance between two maxima was ex- actly twice the line width. In addition, PVDF foil samples were covered with a hydrogel layer in conjunction with RGD peptide se- quence which provided a linker for bone matrix protein (BMP-7) molecules. Results: Lines smaller than 5 lm were not feasible due to the natural irregularity of the basic material with pits and level changes of up to 2 lm. The process showed little debris and constant microstructure shape over the whole structured area (2 Â 2 mm). The resulting debris was examined for toxic by-prod- ucts on human fibrobcytes and chondrocytes. Bioactive nanolayer coating displayed no cytotoxic properties for chondrocyte cell growth, although the impact of surface-bound BMP-7 in contrast to soluble BMP-7 on cell growth is still subject to evaluation. Con- clusion: The results show that microstructures can be applied on titanium surfaces for human implantation with reproducible and constant shapes. Further studies will focus on cell culture of un- coated titanium surfaces which has suggested a relative selectivity for chondrocyte compared to fibrocyte growth in earlier studies, versus bioactive nanolayer coated surfaces. Funding source: This study is being funded by the ‘‘Deutsche Forschungsgemeinschaft” (German Research Foundation), Transregio 37 (Aachen-Hannover- Rostock), Project B3. doi:10.1016/j.heares.2010.03.020 Prosthetic reconstruction to the stapes head or to the stapes footplate? A laser doppler study Wael A. Alian 1,2,3 , Osama F. Majdalawieh 1,4 , Rene G. Van Wijhe 1 , Manohar Bance 1,3,4 1 The Ear & Auditory Research (EAR) Laboratory, Department of Anatomy & Neurobiology, Dalhousie University, Sir Charles Tupper Building Room 12B, 5859 University Ave., Halifax, NS, Canada B3H 4H7; 2 Department of Otolaryngology and Head and Neck Surgery, Sahlgrenska University Hospital, Göteborg University, Göteborg S-413 45, Sweden; 3 Division of Otolaryngology, Department of Surgery, Dalhousie University, 3184 Dickson Building VGH Site, QEII HSC, 1278 Tower Road, Halifax, NS, Canada B3H 2Y9; 4 School of Biomedical Engineering (SBME), Dalhousie University, 5981 University Ave., Halifax, NS, Canada B3H 3J5 Background: It is generally accepted that with a missing incus, reconstruction to the stapes head is more effective than recon- 236 Abstracts / Hearing Research 263 (2010) 233–252